Heart wall ablation/mapping catheter and method

ABSTRACT

A catheter suitable for use in applying ablation energy to body tissue or detecting electrical signals conducted within the body tissue is disclosed. The catheter has a deflectable distal tip section. At least one electrode is adapted to be disposed against body tissue for delivery of ablation energy thereto or for conduction of body tissue electrical signals. An actuation mechanism comprising first and second pull wires is adapted to curve a proximal segment in a first direction and to independently bend an intermediate segment in a second direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/721,895, filed Mar. 11, 2010, now abandoned which is a divisionalapplication of U.S. application Ser. No. 11/115,028, filed Apr. 26,2006, now U.S. Pat. No. 7,706,894, which is a continuation of U.S.application Ser. No. 09/685,193, filed on Oct. 10, 2000, now U.S. Pat.No. 6,926,669, the disclosures of which are incorporated by reference intheir entirety herein.

FIELD OF THE INVENTION

The present invention relates generally to steerable catheters, and morespecifically to steerable electrophysiology catheters for use in mappingand/or ablation of accessory pathways in myocardial tissue of the heartwall.

BACKGROUND OF THE INVENTION

The heart includes a number of pathways through which electrical signalsnecessary for normal, electrical and mechanical synchronous function orthe upper and lower heart chambers propagate. Tachycardia, that isabnormally rapid rhythms of the heart, are caused by the presence of anarrhythmogenic site or accessory pathway which bypasses or shortcircuits the nodal pathways in the heart. Tachycardias may becategorized as ventricular tachycardias (VTs) or supraventriculartachycardias (SVTs). The most common SVT's include atrioventricularnodal reentrant tachycardia (AVNRT), Atrioventricular reentranttachycardia (AVRT), atrial fibrillation (AF), and atrial flutter (AFl).Reentrant tachycardias originate in the atria and are typically causedby an accessory pathway or inappropriate premature return excitationfrom the ventricle through the AV node or left sided accessory pathway.Conditions such as AF and AFl involve either premature excitation fromfocal ectopic sites within the atria or excitations coming throughinter-atrial reentry pathways as well as regions of slow conductionwithin the atria. VT's originate from within the ventricles and havetheir entire circuit contained within the ventricles. These VT's includebundle branch reentrant tachycardia (BBR), right ventricular outflowtract tachycardia (RVOT), and ventricular fibrillation (VF). VT's areoften caused by arrhythmogenic sites associated with a prior myocardialinfarction as well as reentrant pathways between the ventricles. BBRinvolves an inappropriate conduction circuit that uses the right andleft bundle branches. RVOT can be described as a tachycardia originatingfrom the right ventricular outflow tract which involves ectopictriggering or reentry mechanisms. VF is a life threatening conditionwhere the ventricles entertain a continuous uncoordinated series ofcontractions that cause a cessation of blood flow from the heart. Ifnormal sinus rhythm is not restored, the condition is terminal.

Treatment of both SVTs and VTs may be accomplished by a variety ofapproaches, including drugs, surgery, implantable electricalstimulators, and catheter ablation of cardiac tissue of an effectedpathway. While drugs may be the treatment of choice for many patients,drugs typically only mask the symptoms and do not cure the underlyingcause. Implantable electrical stimulators, e.g., pacemakers, afferantnerve stimulators and cardioverter/defibrillators, usually can onlycorrect an arrhythmia after it occurs and is successfully detected.Surgical and catheter-based treatments, in contrast, will actually curethe problem usually by ablating the abnormal arrhythmogenic tissue oraccessory pathway responsible for the tachycardia. The catheter-basedtreatments rely on the application of various destructive energy sourcesto the target tissue including direct current electrical energy, radiofrequency (RF) electrical energy, laser energy, ultrasound, microwaves,and the like.

RF ablation protocols have proven to be highly effective in treatment ofmany cardiac arrhythmias while exposing the patient to minimum sideeffects and risks. RF catheter ablation is generally performed after aninitial electrophysiologic (EP) mapping procedure is conducted using anEP mapping catheter to locate the arrhythmogenic sites and accessorypathways. After EP mapping, an RF ablation catheter having a suitableelectrode is introduced to the appropriate heart chamber and manipulatedso that the electrode lies proximate the target tissue. Such cathetersdesigned for mapping and ablation, frequently include one or morecylindrical or band-shaped individual electrodes mounted to the distalsection of the catheter so as to facilitate mapping of a wider area inless time, or to improve access to target sites for ablation. RF energyis then applied through the electrode(s) to the cardiac tissue to ablatea region of the tissue that forms part of the arrhythmogenic site or theaccessory pathway.

Ablation of VT's can be difficult due to the thickness of theventricular chamber walls. Typical RF delivery through standardelectrodes is not capable of creating deep transmural lesions in theventricles. When RF power is raised to high levels, tissue charring andsubsurface steam explosions can occur. Coagulum buildup on the electrodesurfaces leads to high impedance problems and more importantly, thrombimay be released that could cause stroke. These factors present majorproblems that limit the safe depth to which lesions can be created. Toovercome these problems, saline irrigated electrodes were developed toallow more efficient RF delivery to the myocardium. These irrigatedsystems nearly eliminate coagulum buildup that would cause impedancerises and increase the risk of stroke. Irrigation keeps the metallicelectrodes cool which prevents endocardial surface charring and tissuedessication. With irrigated RF ablation, there remains the problem ofcreating excessive subsurface temperatures that can lead to steamexplosions and cratering of the endocardium.

The following remarks generally apply to catheters designed to performeither one or both of the EP mapping and RF ablation functions, unlessotherwise expressly indicated. Illustrative catheters of this type aredescribed in commonly assigned U.S. Pat. Nos. 5,318,525, 5,545,200 and5,823,955, for example. As described therein, it is frequently desirableto deflect a distal tip section of the catheter body into a non-linearconfiguration such as a semicircle or curved configuration, whichfacilitates access to the endocardial heart wall to be mapped orablated. Such deflection may be accomplished through the use of pullwires secured along the distal tip section which can be tensioned by acontrol on the handle at the proximal end of the catheter to deflect thetip in the desired configuration. In addition, rotational positioning ofthe distal tip section is accomplished, either by rotating the entirecatheter from the proximal end, or by exerting torque on a core wiresecured to the distal tip without rotating the catheter body itself asdisclosed in the above-referenced '525 patent. Moreover, selectivelyretractable stiffening or deflecting core wires are also employed in thedesign of such catheters as shown in the above-referenced '200 patentfor example.

Such mapping and ablation catheters are inserted into a major vein orartery, usually in the neck or groin area, and guided into the chambersof the heart by appropriate manipulation through the vein or artery. Thecatheter must have a great deal of flexibility or steerability to beadvanced through the vascular system into a chamber of the heart, andthe catheter must permit user manipulation of the tip even when thecatheter body traverses a curved and twisted vascular access pathway.Such catheters must facilitate manipulation of the distal tip so thatthe distal electrode(s) can be positioned and held against the tissueregion to be mapped or ablated.

While EP mapping and RF ablation catheters having the aforementioneddeflectability and steerability have had promising results, suchcatheters suffer from certain disadvantages. The catheters disclosed inthe '200 patent provide a continuous curve of the distal tip sectionhaving a selectable radius so that the plurality of ring-shapedelectrodes are distributed in a desired curved to bear against the heartwall at certain sites. The above-referenced, commonly assigned '200 and'955 patents have at least two segments in the distal tip section of thecatheter body that are independently variable. The '955 patent disclosesa curvature of the proximal segment of the distal section in onedirection, and the distal segment of the distal section in the oppositedirection but in the same plane as the proximal segment. The '955 patentdistal tip section configuration is particularly adapted for mapping andablation of tissues around the right and left heart atrioventricular(AV) valve annulus. The '200 patent also discloses a curvature of thedistal segment of the distal section in a lateral direction, out of theplane of the curvature established independently in the proximal segmentof the distal section. The degree of deflection of the distal segmentwith respect to the proximal segment is limited, and the curves that canbe obtained in the distal segment are limited. Moreover, the limitedcurvature or angular displacement of the distal segment with respect tothe proximal segment and the proximal section of the catheter body doesnot make it possible to optimally apply the distal tip electrode(s)against other target points or sites of the heart wall or endocardium.

A steerable catheter for mapping and/or ablation is needed that enablesmapping and ablation about a variety of structures of the heartcomprising particularly about various vascular orifices or valvesentering the right and left atria and the valves between the atria andventricles.

Furthermore, there is a need for a catheter having the capability ofabruptly changing the angle of the tip electrode(s) bearing segment withrespect to the more proximal catheter shaft in order to enable fulllength tissue contact of the side of an elongated electrode or set ofelectrodes with the heart tissue to be mapped or ablated.

SUMMARY OF THE INVENTION

The present invention is directed to a steerable catheter for mappingand/or ablation that comprises a catheter body having a proximal sectionand a distal section, a handle coupled to he proximal end of thecatheter body, and manipulators that enable the deflection of a distalsegment of the distal tip section with respect to a proximal segment ofthe distal tip section or the proximal section. The manipulators enableindependently imparting a curvature of the proximal segment and abending or knuckle motion of an intermediate segment between theproximal and distal segments. A wide angular range of deflection withina very small knuckle curve or bend radius in the intermediate segment isobtained. At least one distal tip electrode is preferably confined tothe distal segment which can have a straight distal segment axis or canhave a pre-formed curvature of the distal segment axis extendingdistally from the intermediate segment.

The manipulators preferably comprise a proximal curve forming pull wireand a knuckle bend forming pull wire extending from manipulator elementsof the handle to the proximal and intermediate segments that enableindependently forming the curvature in the proximal segment and knucklebend in the intermediate segment in the same direction and in the sameplane. The axial alignment of the distal segment with respect to theaxis of the proximal shaft section of the catheter body can be varied bypulling proximally on the knuckle bend forming pull wire betweensubstantially axially aligned (0°) to a substantially side-by-sidealignment accomplished by a substantially +180° bending curvature of theintermediate segment within a bending radius of between 2.0 mm and 7.0mm and preferably less than 5.0 mm. The possible range of positivecurvature of the proximal segment with respect to the catheter body axis(0° reference) is to about +270° when the proximal curve forming pullwire is pulled proximally.

Alternatively, the manipulators preferably comprise a proximal curveforming push-pull wire and/or a knuckle bend forming push-pull wireextending from manipulator elements of the handle to the proximal andintermediate segments that enable independently forming the curvature inthe proximal segment and knuckle bend in the intermediate segment in thesame or opposite directions direction but in the same plane. The axialalignment of the distal segment with respect to the axis of the proximalshaft section of the catheter body can be varied by pushing distally onthe knuckle bend forming pull wire. By pushing, an abrupt knuckle bendcan be formed in the intermediate segment ranging from substantially 0°to about −90° within the bending radius of between 2.0 mm and 7.0 mm andpreferably less than 5.0 mm. Similarly, a negative curvature can beformed in the proximal segment by pushing the proximal curve formingpush-pull wire. The possible range of curvature of the proximal segmentwith respect to the catheter body axis (0° reference) is tosubstantially −90° when the push-pull wire is pushed distally.

In one preferred embodiment, the pull wires or push-pull wires traverselumens in the catheter body that are offset from the catheter body axisin a common radial direction so that the positive curve formed in theproximal segment and the knuckle bend formed in the intermediate segmentare in the same direction.

The ranges of knuckle bend and proximal segment curvature can be limitedduring manufacture by selection of range of movement of the manipulatorelements of the handle to provide desirable deflections to optimallyaccess particular sites of the heart for mapping or ablation. Theindependently formed curvature of the proximal segment and small radiusknuckle bend of the intermediate segment provides a wide variety ofoptimal configurations for making firm contact with certain sites ofectopic foci, arrhythmia sustaining substrates or accessory pathways ofinterest in the heart. These sites include those adjacent to theEustachian ridge, the AV node, the triangle of Koch in the right atrium,those encircling the orifices of the pulmonary veins in the left atrium,and those accessed under the cusps of the mitral valve in the leftventricle.

In a further preferred embodiment, the distal segment of the distalsection of the catheter body is configured to elastically conform to theseptal wall extending from the Eustachian ridge to the tricuspid valveannulus including the caval-tricuspid isthmus when a knuckle bend isformed in the intermediate segment that hooks over the Eustachian ridgeat the orifice of the inferior vena cava. In this embodiment, theproximal segment and proximal segment manipulators can be eliminated ornot employed.

The curvature of the proximal segment and the bending angle of theintermediate segment are independently selectable by the physician byindependently operating the separate manipulators. Thus, when a suitablebend or curvature is formed in the intermediate and proximal segments,it is not unduly affected when the other of the curvature or bend ischanged.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will becomeapparent from the following description in which the preferredembodiments are disclosed in detail in conjunction with the accompanyingdrawings in which:

FIG. 1 is an overall view of one embodiment of an ablation and/or EPmapping catheter made according to the invention which can accommodate avariety of electrode configurations;

FIGS. 2-7 are simplified views of the distal section of the catheterbody of FIG. 1 showing the movement of the proximal, intermediate anddistal segments from the straight, dashed line position to the depictedcurved positions;

FIG. 8 is an exploded perspective view of the principal components ofthe catheter body of FIG. 1;

FIG. 9 is a side cross-section view of the junction of the distal andintermediate segments and the intermediate segment tube of the distalsection of the catheter body of FIG. 1;

FIG. 10 is an end cross-section view along lines 10-10 of FIG. 9depicting the internal structure of a distal insulator member at thejunction of the distal and intermediate segments of the distal sectionof the catheter body of FIG. 1;

FIG. 11 is an end cross-section view along lines 11-11 of FIG. 9depicting the internal structure of the intermediate segment tube of thedistal section of the catheter body of FIG. 1;

FIG. 12 is a side cross-section view of the junction of the proximal andintermediate segments and the proximal segment tube of the distalsection of the catheter body of FIG. 1;

FIG. 13 is an end cross-section view along lines 13-13 of FIG. 12depicting the internal structure of a proximal insulator member at thejunction of the proximal and intermediate segments of the distal sectionof the catheter body of FIG. 1;

FIG. 14 is an end cross-section view along lines 14-14 of FIG. 12depicting the internal structure of the proximal segment tube of thedistal section of the catheter body of FIG. 1;

FIG. 15 is a side cross-section view of the junction of the proximalsegment with the distal end of the proximal section as well as of theproximal section of the catheter body of FIG. 1;

FIG. 16 is an end cross-section view along lines 16-16 of FIG. 15depicting the internal structure of the proximal section of the catheterbody of FIG. 1;

FIG. 17 is a partial perspective view of a frame of the handle depictingthe junction of the proximal end of the catheter body with the distalend of the handle showing the proximal ends of the incompressible coilssurrounding proximal portions of the knuckle deflection push-pull wireand the curve deflection push-pull wire abutting a disk allowing theincompressible coils to float;

FIGS. 18-20 are schematic illustrations of the selective locations ofthe distal section of the catheter of FIG. 1 for cardiac mapping and/orablation;

FIG. 21 is a partial perspective exploded view of a further embodimentof the distal segment of the distal section of the catheter body adaptedfor use in mapping and ablating the heart wall along the Caval-tricuspidisthmus;

FIGS. 22 and 23 are simplified views of the distal section of thecatheter body of FIG. 21 showing the movement of the proximal,intermediate and distal segments from the straight position to thedepicted curved position;

FIG. 24 is a partial perspective exploded view of a still furtherembodiment of the distal segment of the distal section of the catheterbody adapted for use in mapping and ablating the heart wall along theCaval-tricuspid isthmus;

FIGS. 25 and 26 are simplified views of the distal section of thecatheter body of FIG. 24 showing the movement of the proximal,intermediate and distal segments from the straight position to thedepicted curved position; and

FIG. 27 is a schematic illustration of the location of the distalsection of the catheter of FIGS. 21-25 for cardiac mapping and/orablation along the Caval-tricuspid isthmus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically illustrates an anatomically-conforming, multi-curvecatheter 10 incorporating various features of the present invention fororienting a distal tip electrode 12 (or electrodes) with respect to theheart wall for RF ablation and/or EP mapping. The multi-curve catheter10 can incorporate a porous tip and catheter lumen for emittingirrigating fluid around the distal tip electrode 12, but those featuresare not illustrated in FIG. 1 to simplify illustration. Moreover, thedistal segment 32 is simplified in FIG. 1 to show an elongated tubularshaped ablation electrode 12 and a pair of mapping electrodes 13 and 15in the illustration of FIG. 1, but the distal segment 32 may comprise aplurality of ring-shaped electrodes, one or more coil electrode or thelike having other shapes that are presently used or may come into useand including several variations described below in reference to otherfigures. It will be understood that the catheter 10 also represents anablation catheter construction delivering other forms of ablationenergy, including visible or invisible light, infrared, and electricalenergy from or along the distal tip.

The catheter 10 comprises a catheter shaft or body 20 and a handle 40.The catheter shaft or body 20 has a shaft axis 24 and extends between adistal end 26 and a proximal end 28 and is separated into a proximalsection 22 and a distal section 30. Catheter body 20 may be of anysuitable diameter and length and may be straight or pre-curved along itslength, but preferably is straight when unrestrained. The distal section30 or the distal segment thereof can be tapered from the diameter of theproximal section 22. Preferably, the catheter body 20 has a uniformoutside diameter of about 0.052 inch (1.32 mm) to 0.1040 inch (2.64 mm)and a length of about 50 cm to 110 cm.

The proximal section 22 has sufficient column strength and is capable ofgood torque transmission to permit controlled placement of the distalsection 30 at a target site in the heart including a selected cardiacvalve or vessel in the manners discussed below. The distal section 30 isdeflectable away from shaft axis 24 and includes a distal segment 32, acurvable proximal segment 36 having a proximal segment length, and abendable intermediate segment 34 having an intermediate segment lengthdisposed between the distal segment 32 and the curvable proximal segment36. The illustrative tip electrode 12 is positioned along the distalsegment 32, preferably extending proximally from the catheter bodydistal end 26 through all or part of the length of the distal segment32. The distal segment 32 can include an elongated ablation electrode 12that may be solid or irrigated and can include one or more proximal ringelectrodes 13, 15 for use in mapping that are either located proximallyas shown or distally from ablation electrode 12. Each electrode isseparately connected to insulated conductors extending proximallythrough the catheter body 20 to terminals of a cable connector in or onthe handle 40 that is connected via a cable to the ablation energysource and/or mapping signal amplifiers. As described further below, athermocouple is also typically included in the distal segment 32 of suchablation catheters, and separately insulated thermocouple conductorsextending proximally through the catheter body 20 to terminals of thecable connector in or on the handle 40 that are coupled via a cable tothe temperature display and ablation energy control apparatus known inthe art.

The handle 40 can take any of the forms known in the art for makingelectrical connections with the conductors within the catheter body 20,for delivering irrigation fluid to an irrigation lumen (if present) ofthe catheter body 20. The handle 40 also comprises a mechanism fordeflecting the distal tip section 30 into the shapes provided by thepresent invention. The mechanism can take any form for pulling, pushingand/or twisting the deflection or push/pull wires within the catheterbody 20 as described further below. In the illustrated embodiment, thehandle 40 is attached to the catheter body proximal end 28 and supportsaxially slidable manipulators comprising push-pull rings 44 and 46 and arotatable lateral deflection ring 42 that are coupled to the proximalends of a curve deflection push-pull wire, a knuckle deflectionpush-pull wire, and a lateral deflection wire identified and describedfurther below. The lateral deflection ring 42 can be rotated to impart atorque in a lateral deflection wire coupled thereto to laterally rotatethe distal section 30 with respect to axis 24 within the proximalsection 22. The details of construction of one embodiment of thecomponents of the catheter body 20 are set forth in FIGS. 8-16 and thesecurve and rotation functions are described further below.

As shown in FIG. 1, when the push-pull wires are relaxed, the distalsegment 32, the bendable intermediate segment 34, and the curvableproximal segment 36 are aligned with the shaft axis 24 which isreferenced as 0°. The knuckle deflection push-pull wire can be retractedor pulled by sliding ring 46 proximally to impart a small radius bendfrom substantially 0°, wherein the distal and proximal segments 32 and36 are axially aligned, to substantially 180°, whereby the distal andproximal segments 32 and 36 are substantially in side-by-side alignment.The knuckle deflection push-pull wire can be extended or pushed bysliding push-pull ring 46 distally to impart a small radius bend fromsubstantially 0° to about −90°, that is in a bend direction opposite tothe bend direction imparted when the knuckle deflection push-pull wireis retracted or pulled by sliding ring 46 proximally. The intermediatesegment 34 is bent in a bending radius of between 2.0 mm and 7.0 mm, andpreferably less than about 5.0 mm within the bending angle range. Theabrupt knuckle bend angle range can be restricted further by positioningof the slide end stops for the push-pull ring 46 during assembly.

The manipulator push-pull ring 44 can be moved proximally or distally tomove the curve deflection push-pull wire coupled thereto proximally ordistally to form a curve in the proximal segment 36 that is opposed toor in the same direction as the bend imparted in the intermediatesegment 34. The bend or curve of the proximal segment 36 that can beinduced relative to the catheter body axis 24 as depicted in the figurescan be between −90° to +270° relative to the proximal section 22. Thecurvature range of the proximal segment 36 can be restricted further byposition of the slide end stops for the push-pull ring 44 duringassembly.

FIGS. 2 through 7 illustrate four of many possible co-planar curvesinduced in the segments of the distal section 30 in relation to thecatheter body axis 24 accomplished by selective movement of the axiallyslidable manipulator rings 46 and 44 coupled to the knuckle deflectionpush-pull wire 56 and the curve deflection push-pull wire 54,respectively. The distal end of the knuckle deflection push-pull wire 56terminates at the junction of the intermediate segment 34 with thedistal segment 32, and the curve deflection push-pull wire 54 terminatesat the junction of the intermediate segment 34 with the proximal segment36. The knuckle deflection push-pull wire 56 and the curve deflectionpush-pull wire 54 extend in parallel with and are radially aligned tothe catheter body axis 24 along a common radius extending from thecatheter body axis 24 through the proximal section 22 and the proximalsegment 36. The knuckle deflection push-pull wire 56 is spaced furtheraway from the axis 24 than the curve deflection push-pull wire 54through the proximal section 22 and proximal segment 36. The distalsection of the knuckle deflection push-pull wire 56 traversing theintermediate segment 34 is axially aligned with the axis of the curvedeflection push-pull wire 54 in the proximal segment 36.

In FIG. 2, both the knuckle deflection push-pull wire 56 and the curvedeflection push-pull wire 54 are pulled proximally to induce a shortradius, 90° knuckle bend in the intermediate segment 34 and a longradius curve in the same plane and direction in the proximal segment 36.A 90° bend of the intermediate segment 34 with respect to the proximalshaft section 22 provides an optimum angular orientation of the distalelectrode 12 for pushing or pulling it against the heart wall.

FIG. 3 illustrates the same short radius, 90° knuckle bend formed in theintermediate segment 34 but without any curvature formed in the proximalsegment 36. As set forth above, a knuckle bending radius between 2.0 mmand 7.0 mm and preferably less than about 5.0 mm is provided.

FIG. 4 illustrates the full substantially 180° knuckle bend formed inthe intermediate segment 34 without any curvature formed in the proximalsegment 36, so that the distal and proximal segments 32 and 36 aresubstantially in side-by-side orientation.

The curve deflection push-pull wire 54 can be both pulled proximally asshown in FIG. 2 to induce a curvature in the same direction as theknuckle bend in intermediate segment 34 and pushed distally as shown inFIG. 5 to induce a curvature in the opposite direction as the knucklebend in intermediate segment 34. The curvature that can be induced inthe proximal section ranges from −90° to +270° relative to the proximalsection 22 and with respect to catheter body straight axis 24, butsmaller ranges can be selected.

FIG. 6 illustrates a +270° curvature in the distal section 22 effectedby retraction of both push-pull wires 54 and 56, and FIG. 7 illustratesa +270° curvature in the distal section 22 effected by retraction ofonly curve deflection push-pull wire 5. In this way, the distalelectrode 12 is positioned at −90° to the proximal section 22, which isa useful orientation for ablating or mapping the heart wall at thecaval-tricuspid isthmus or sites under in the ventricles the mitral ortricuspid valve flaps.

The lateral deflection that can also be induced to orient the distal tipelectrode 12 out of the plane of FIGS. 2-7 using the lateral deflectionwire 52 and manipulator ring 42 is not shown in these figures since itwould be out of the plane of the paper that the drawings are printed on.When the ring 42 is rotated clockwise or counterclockwise, the lateraldeflection wire is twisted, causing the junction of the proximal andintermediate segments 36 and 34 to rotate. It will be understood fromthe construction of the lateral deflection wire described below that alateral deflection of the tip segment 32 and the intermediate segment 34in the range of −90° to +90° with respect to catheter body straight axis24 can be achieved by such rotation.

The structure of the catheter body 20 that achieves these angular tipsection deflections and the lateral deflection is illustrated in FIGS.8-16. FIGS. 9-16 also show the internal arrangement of the pull wiresand wire lumens as well as the wires that apply RF energy to the tipelectrode 12 and a thermocouple located in a cavity in the tip electrode12.

The proximal section 22 shown in FIGS. 8 and 15-16, is formed of anouter shaft jacket or sheath 50, preferably made of high durometer (suchas 72D) Pebax® reinforced by a braided wire tubing formed of flat,stainless steel wire embedded within the sheath wall that encloses asheath lumen 58. Pebax® polyamide polyether block copolymer is made byElf Atochem, Inc. of Philadelphia, Pa. The sheath lumen 58 encloses theknuckle deflection push-pull wire 56, the curve deflection push-pullwire 54, and the lateral deflection wire 52. The sheath lumen 58 alsoreceives the distal tip electrode conductor 70 extending between thehandle 40 and the distal tip electrode 12 and thermocouple wires 72 and74 that extend between a thermocouple 90 (depicted in FIG. 9) andtemperature monitoring circuitry of the RF energy generator. Thethermocouple 90 provides temperature readings to modulate the deliveredenergy level or duty cycle to avoid undue heating of the distal tipelectrode 12 during ablation. The distal tip electrode conductor 70 isused to convey electrical signals of the heart sensed through the tipelectrode 12 to ECG display equipment coupled to a terminal of thehandle 40 during EP mapping or to deliver the RF energy from the RFenergy generator to the distal tip electrode 12. These conductors 70, 72and 74 would be separately electrically insulated from one another andthe knuckle deflection push-pull wire 56, the curve deflection push-pullwire 54, and the lateral deflection wire 52. It will be understood thatthe lumen 58 can be configured with a fluid conduit to direct irrigationfluid to irrigation ports of the distal tip electrode 12 and can be usedto carry further wires coupled to additional, more proximally or moredistally located, EP mapping and/or ablation electrodes than electrode12.

The knuckle deflection push-pull wire 56 and the curve deflectionpush-pull wire 54 are encased within incompressible spiral wire tubes 66and 64, respectively, that extend from proximal tube ends abutting astop plate within the distal end of handle 40 distally through theproximal sheath lumen 58. A distal section of the incompressible spiralwire tube 66 and knuckle deflection push-pull wire 56 extends distallyfrom junction 59 of the proximal section 22 and proximal segment 36through a lumen 68 of proximal segment tube 60. The distal end of theincompressible spiral wire tube 66 is located abutting the proximalinsulator 80 shown in FIGS. 8, 12 and 13 that the knuckle deflectionpush-pull wire 56 passes through, and it is adhered to the proximalinsulator 80 when the proximal insulator is thermally bonded between thetubes 60 and 82. The incompressible spiral wire tube 66 is not attachedat its proximal end to the handle 40, and it therefore “floats” over theproximal portion of the knuckle deflection push-pull wire 56 thattraverses the catheter body proximal section 22 and the proximal section36 of the distal section 30. This floating feature advantageouslyprevents the stretching of the coil turns of the incompressible spiralwire tube 64 when the knuckle deflection push-pull wire 56 is pushed orwhen the adjacent curve deflection push-pull wire 54 is pushed distallyor pulled proximally, inducing a curve in the proximal segment 36.

The distal end of the incompressible spiral wire tube 64 is located atthe junction 59 of the distal end of proximal sheath 50 with theproximal end of the multi-lumen tube 60 of the proximal segment 36 shownin FIGS. 8 and 15. The junction 59 is a butt welded junction of thedistal end of proximal sheath 50 with the proximal end of themulti-lumen tube 60, and so the distal end of the incompressible spiralwire tube 66 is affixed to junction 59 by the solidification of themelted material to it. But, the proximal end of the incompressiblespiral wire tube 66 is not attached to the handle 40, so that the coilturns of the incompressible spiral wire tube 66 when the curvedeflection push-pull wire 54 is pushed or when the adjacent knuckledeflection push-pull wire 56 is pushed distally or pulled proximally,inducing a curve in the intermediate segment 34.

The incompressible spiral wire tubes 64 and 66 are preferably formed ofstainless steel flat wire wound so that the narrow wire edges abut oneanother in each turn, but do not overlap one another when the coils arecompressed by pulling proximally on the curve deflection push-pull wire54 and the knuckle bend push-pull wire 56. The coil turns of coilsformed of circular cross-section wire tends to ride over one another.Preferably, the incompressible spiral wire 64 is 0.017 inches thick by0.023 inches wide, and the incompressible spiral wire 66 is 0.013 inchesthick by 0.019 inches wide. The coil turns are close wound so that thethinner wire sides of each coil turn abut or nearly abut one another.

The knuckle deflection push-pull wire 56 is formed of a nickel-titaniumsuperelastic metal that has a straight memory shape and does not readilykink, enabling the repeated formation of small radius knuckle bends inthe intermediate segment 34 as described further below. The curvedeflection push-pull wire 54 and the lateral deflection wire 52 areformed of stainless steel, and their distal ends are both attached tothe proximal insulator member 80. The lateral deflection wire 52 istapered and is reduced in diameter distally when it traverses theproximal segment 36. Wires 52, 54 and 56 are preferably coated with alubricious material, e.g. PTFE or Parylene, to reduce sliding friction.

As shown in FIG. 8, the distal section 30 is formed of the distalelectrode 12 and distal insulator 84 together forming the distal segment32. The intermediate segment 34 is formed of the two-lumen intermediatetube 82 and includes the distal section of knuckle deflection push-pullwire 54. The proximal segment 36 is formed of the multi-lumen tube 60and proximal insulator 80 along with the wires passing through theirlumens. The multi-lumen tube 60 is preferably formed of intermediatedurometer (such as 55D) Pebax® polyamide polyether block copolymer. Theproximal insulator 80 illustrated in cross-section in FIGS. 12 and 13 isformed of a relatively rigid PEEK (polyether-ether-ketone) or otherhard, temperature-resistant material with a number of lumens 81, 83, 85and 86 extending through it aligned axially with the lumens 63, 65 and68 of multi-lumen tube 60 and lumens 88 and 93 of two-lumen intermediatetube 82.

The proximal end of the multi-lumen tube 60 is butt welded to the distalend of proximal sheath 50 at the junction 59 as described above and thevarious conductors and wires are directed through the lumens 63, 65 and68 as shown in FIG. 14. The knuckle deflection push-pull wire 56 andincompressible spiral wire 66 are directed through elliptical lumen 68along with the conductors 70, 72 and 74. The incompressible spiral wire66 terminates in abutment against the proximal insulator 80, but theknuckle deflection push-pull wire extends distally through the proximalinsulator 80. The curve deflection push-pull wire 54 is extendeddistally through the lumen 63 to an attachment with the proximalinsulator 80, but the distal end of the incompressible spiral wire 64 isterminated at junction 59 as described above. The lateral deflectionwire 52 extends distally through lumen 65 to a connection with theproximal insulator 80. Additional lumens can also be provided in tube 60that make the tube 60 more flexible and easier to bend.

The two-lumen intermediate tube 82 is preferably formed of relativelysoft durometer (such as 35D) Pebax® polyamide polyether block copolymer.The conductors 70, 72 and 74 pass through the central lumen 86 and intoa lumen 88 of the two-lumen intermediate tube 82. The knuckle deflectionpush-pull wire 56 extends distally through lumen 83 of the proximalinsulator 80. The curve deflection push-pull wire 54 within lumen 68extends distally through the lumen 81 where its distal end is bent overand attached to the distal surface of the proximal insulator 80.Similarly, the lateral deflection wire 52 in lumen 65 extends distallythrough lumen 85 where its distal end is bent over and attached to thedistal surface of the proximal insulator 80.

During manufacture, the lumens 93 and 88 of the two-lumen intermediatetube 82 are aligned with the lumens 83 and 86, respectively, of proximalinsulator 80 as shown in FIGS. 11 and 13 which are aligned with thecentral lumen 68 of the multi-lumen tube 60 and the wires are passedthrough them as described above. The lumens 63 and 65 of the multi-lumentube 60 are aligned with the lumens 81 and 85 of proximal insulator 80,and the wires 54 and 52 are passed through the aligned lumens asdescribed above. Heat and pressure are applied to the assembly to fusethe proximal insulator 80 between the proximal end of the two lumenintermediate tube 82 and the distal end of the multi-lumen proximal tube60. The applied heat causes the tube material to flow over scallopedsections of the outer surface of proximal insulator 80 thereby fusingthe proximal end of the two lumen intermediate tube 82 with the distalend of the multi-lumen proximal tube 60.

The distal insulator 84 illustrated in cross-section in FIGS. 9 and 10is formed of a relatively rigid PEEK or other hard,temperature-resistant material and is attached between tube 82 anddistal tip electrode 12 preferably using a mechanical interlock and/oradhesive. The distal end of two lumen intermediate tube 82 is shaped tofit over and be adhered through the use of appropriated adhesive,thermal bond, or other appropriate methods to the proximal end of thedistal insulator 84 after aligning the lumen 93 with the lumen 87 ofdistal insulator 84. The conductors 70, 72 and 74 pass through thecentral lumen 88 of the two-lumen intermediate tube 82 and through acentral lumen 89 of the distal insulator 84 as shown in FIGS. 9-11. Thedistal end of the distal insulator 84 extending through lumen 89 isattached to the distal tip electrode 12 as shown in FIG. 9, and theconductor 70 is butt welded to the distal tip electrode 12. The distalends of the thermocouple conductors 72 and 74 extend through lumen 89and are attached to the thermocouple 90 positioned within a cavity ofthe distal tip electrode 12 as shown in FIG. 14. The knuckle deflectionpush-pull wire 56 extends distally through lumen 87 of the distalinsulator 84. The enlarged diameter distal ball-tip end 57 of theknuckle bend pull wire 56 fits into a bore 95 of the distal insulator 84so that the distal end of knuckle bend pull wire 56 is fixed in place.

FIG. 17 is a partial perspective view of the distal end of an interiorframe member 41 and a coil wire stop plate 43 within the distal end ofthe handle 40 that is joined with the proximal end of the catheter body20. FIG. 17 shows that the proximal ends of the incompressible coils 66and 64 surrounding proximal portions of the knuckle deflection push-pullwire 56 and the curve deflection push-pull wire 54, respectively, simplyabut the plate 43. The proximal portions of the knuckle deflectionpush-pull wire 56, the curve deflection push-pull wire 54, and thelateral deflection wire 52 pass through holes in the plate 43. Theincompressible coils 66 and 64 are not otherwise restrained so that theincompressible coils 66 and 64 can move away from the plate 56 and notbe stretched if the catheter body 20 is extended distally. In this way,the knuckle deflection push-pull wire 56 and the curve deflectionpush-pull wire 54 can be extended or pushed distally to impart thenegative curvature in the intermediate and proximal segments 34 and 36without stretching the incompressible coils 66 and 64.

Handle 40 may be of a conventional design, e.g. as shown in theabove-referenced, commonly assigned '200 patent, except for the plate 56and its above described function. Handle 40 also includes an electricalconnector connected to electrical conductors 70, 72 and 74 (and anyadditional conductors) for connection with a cable that is attached tothe ECG and/or ablation equipment. Handle 40 may also be configured tobe coupled with a source of irrigation fluid if the catheter body 20 andelectrode 12 are modified to provide an irrigation fluid lumen and portsthrough the electrode 12.

Returning to the bendable intermediate segment 34, the relativelyflexible tube 82 is thus bounded on its proximal end by the proximalinsulator 80 and on its distal end by the distal insulator 84. Thelength of the tube 82 and the distal section of the knuckle deflectionpush-pull wire 56 traversing lumen 93 forming the intermediate segment34 is preferably on the order of about 4.0 mm to 15.0 mm. The length ofthe tube 60 of the proximal segment 36 is preferably on the order ofabout 30.0 mm to 120.0 mm.

The proximal segment 36 can be curved as shown in FIGS. 2, 5, 6 and 7 byretraction of the curve deflection push-pull wire 54 by retractingaxially slidable manipulator ring 44. The proximal retraction of theknuckle bend pull wire 56 by retracting axially slidable manipulatorring 46 induces a knuckle bend in the tube 82 of the intermediatesection 34 as depicted in FIGS. 2-6. independently of the curve inducedin the proximal segment 36. The knuckle bend that is induced has abending radius of less than about 5.0 mm within a bend of substantially180°.

The incompressible spiral coil wires 64 and 66 prevent the compressionof the tube 60 of proximal segment 36 or the sheath 50 of the proximalsection 22. The incompressible spiral wires 64 and 66 are not stretchedor compressed by retraction of one or another of the push-pull wire 54or the knuckle bend pull wire 56 or twisting induced by manipulation ofthe lateral deflection wire 52 because the proximal ends of theincompressible spiral wires 64 and 66 are not attached at the handle 40.

FIGS. 18-20 are schematic illustrations of the selective locations ofthe distal section 30 of the catheter body 20 of the catheter 10described above for cardiac mapping and/or ablation of the heart 100. Inthe following discussion, it will be assumed that the distal tipelectrode 12 is first applied to the location of interest, ECG readingsare made to determine the existence and location of accessory pathways,and ablation is selectively performed.

FIGS. 18-20 illustrate, in simplified form, a sectioned heart 100 andthe major vessels bringing venous blood into the right atrium RA,oxygenated blood into the left atrium LA and the aorta and aortic arch(FIG. 20) receiving oxygenated blood from the left ventricle LV. Thevenous blood is delivered to the RA through the superior vena cava SVC,the inferior vena cava IVC and the coronary sinus CS which all open intothe right atrium RA superior to the annulus of the tricuspid valveleading into the right ventricle. Oxygenated blood from the two lungs isdelivered into the left atrium by the left and right, inferior andsuperior, pulmonary veins LIPV, LSPV, RIPV and RSPV which are superiorto the mitral valve. The right and left atria are separated by aninter-atrial septum and the right and left ventricles are separated by aventricular septum. The tricuspid valve TV and mitral valve MV are notshown completely to simplify the figures.

Accessory pathways develop in several parts of the RA and LA that arereached by the catheter 10 to be mapped and/or ablated in accordancewith methods of use thereof of the present invention depicted, forexample, in FIGS. 18 and 19, respectively. Certain atrial tachycardiasalso employ left-sided accessory pathways in tight areas under the cuspsof the mitral valve MV that can be reached in the manner depicted inFIG. 20. In these illustrations, it will be understood that the catheterbody proximal section is flexible enough so that it curves to traversethe vascular system and is curved within a heart chamber by the heartchamber wall by the catheter body

In FIG. 18, the distal section 30 of the catheter body 20 is introducedinto the RA through the IVC, and the distal segment 32 is oriented toselected locations of the RA heart wall through selective manipulationsof the manipulator rings 42, 44 and 46. The RA is separated into aposterior, smooth walled portion that the SVC, IVC and CS orifices openthrough and a thin walled trabeculated portion separated by a ridge ofmuscle which is most prominent superior to the SVC ostium. Vestigialvalve flaps can adjoin the IVC and CS orifices in some patient's hearts.

A thickened isthmus or Eustachian ridge extends between the IVC orificeand the medial cusp of the tricuspid valve. Certain atrial fluttertachyarrhythmias are known to be caused by accessory pathways situatedin the myocardium at or along the Eustachian ridge toward the annulus ofthe tricuspid valve, and ablation to create a lesion from the IVCorifice over the Eustachian ridge can be used to sever the accessorypathways therein. In FIG. 18, the distal section of the catheter body isformed into a hook shape within the IVC to “hook” the distal tipelectrode over the Eustachian ridge and draw it against the tissue inlocation 1A. A +150° to +180° knuckle bend is made in the intermediatesegment in the manner of FIG. 4 to form this hook shape and access thislocation 1A.

Alternatively, the distal section is advanced into the RA and a +150° to+180° curve is formed in the proximal segment 36 of the distal sectionalong with the +180° knuckle bend made in the intermediate segment inthe combined manner of FIGS. 2 and 4 to access the location 1B. Thecatheter body 20 is then retracted to apply the distal tip electrode 12at the distal end of this compound hook shape against the tissuelocation 1B adjacent or overlying location 1A at the Eustachian ridge.

The heart wall can be mapped and continuous lesions can be made alongthe Eustachian ridge by successively moving the distal electrode 12 toan adjoining location to location 1A or 1B to sense the heart signals orapply RF ablation energy to the new site. The movement can be effectedby twisting the distal segment 32 about the catheter body axis 24 byrotating the lateral deflection manipulator ring and wire and/or byadjusting the curvature in the proximal segment 36.

Other accessory pathways in the inter-atrial septum adjacent the AV nodeor elsewhere along the RA wall or in the triangle of Koch can beaccessed as shown by the exemplary location 1C of the distal tipelectrode. In this illustrated example, a +90° knuckle bend is made inthe intermediate segment in the manner of FIG. 3, and a further positivedirection +90° bend is made in the proximal segment 36. Or, if theentire distal section 30 is within the RA, then the configuration ofFIG. 2 can be employed to locate and hold the distal tip electrodeagainst the atrial wall around the AV node at the exemplary location 1C.

Premature activations occur frequently in the LA wall, particularly frompulmonary venous foci around the annular orifices of certain or all ofthe pulmonary veins RIPV, RSPV, LIPV, LSPV shown in FIG. 19 that causeatrial fibrillation. The LA can be accessed in a retrograde mannerthrough the aorta. However, another convenient approach to the LA is viaa puncture made through the inter-atrial septum from the RA employing atransseptal sheath 38 as depicted in FIG. 19. The distal section 30 canbe formed with about a +90° knuckle bend is made in the intermediatesegment in the manner of FIG. 3 and slight positive, neutral or negativecurvatures in the range of about −45° to +45° in the proximal segment 36as in FIGS. 2, 3, and 4 to align the distal tip to locations 2A, 2B or2C. Continuous lesions can be made around the selected pulmonary valveorifice by successively moving the distal electrode to the next locationand applying RF ablation energy. The movement can be effected bytwisting the distal segment about the catheter body axis using thedeflection wire and manipulator.

The left-sided accessory pathways for atrial tachycardia in tight areasunder the cusps of the mitral valve MV are advantageously accessed byadvancing the distal section 30 of catheter body 20 in a retrogrademanner through the aorta and into the LV and then angling and advancingthe distal tip electrode under the cusps to exemplary location 3 asshown in FIG. 20. The distal segment 32 extends inward in relation tothe plane of the drawing of FIG. 20, and can be worked under the cuspsaround the MV to map and/or ablate a succession of adjoining sites.

While the preferred embodiment only illustrates a singlemapping/ablation distal tip electrode 12 particularly used in a unipolarablation and/or mapping mode, it will be understood that it may beadvantageous to locate one or more additional mapping/ablationelectrodes in the distal segment 32 and/or proximally in the curvableproximal segment 36 for selective operation either in a unipolar orbipolar mapping/ablation mode. In the latter case, bipolarmapping/ablation across or through the Eustachian ridge can be achievedin the hook configuration depicted in FIG. 4 and at location 1A of FIG.18.

In further embodiments of the present invention depicted in FIGS. 21-27,particularly for ablating or mapping the Eustachian ridge, a pluralityof mapping and/or ablation electrodes are located along extended distalsegments 132 and 232 distal to electrode 112 (which can be eliminated invariations to these embodiments). The extended distal segments 132 and232 are formed to comply to the particular shape of the caval-tricuspidisthmus extending anteriorly from the orifice of the IVC and toward thevalve flaps of the tricuspid valve to map and ablate that area as shownin FIG. 27. The extended distal segments 132 and 232 can have apre-formed curved axis particularly shaped to the surface curvature ofthe caval-tricuspid isthmus. Or, the extended distal segments 132 and232 can have an elasticity and flexibility that conforms to the surfacecurvature of the caval-tricuspid isthmus effected by selection of asuitable low durometer insulating tubular member supporting theelectrode(s). In either case, the hook shape is formed in the knucklebend segment 34 in the manner illustrated in FIGS. 24, 26 and 27, and apositive curve can be induced in the proximal segment 36 as shown inFIG. 24 or 26 as necessary. A 0° or negative curvature can alternativelybe induced in the proximal segment 36 as shown in FIG. 5 if foundnecessary in a particular heart. From the handle 40 outside the body, itis therefore possible to hook the intermediate segment 34 over theEustachian ridge to orient the elongated, flexible electrode supportbody of the distal segments 132, 232 against and in conformance withcontours of the heart wall between the Eustachian ridge and thetricuspid valve cusps. A guide sheath or introducer may be required tostraighten the pre-formed curvature or the highly flexible distalsegment 132, 232 to enable introduction through the vascular system andinto the RA.

The extended distal segment 132 is formed of a plurality (e.g. six) ofring electrodes 116, 118, 120, 122, 124, and 126 supported on a highlyflexible or pre-formed electrode support tube 114 as shown in FIGS.21-23. The proximal end of the extended distal segment 132 including thedistal insulator 84 is coupled to the intermediate segment 34 of thecatheter otherwise shown in FIGS. 1 and 8-17 and described above. Afurther insulator 130 separates electrode 112 from the electrode supporttube 114, and the distal tip 128 is fitted to the distal end of theelectrode support tube 114. The conductors to the electrodes 116, 118,120, 122, 124, and 126 that traverse the lumens of the electrode supporttube 114, the insulator 130, the electrode 112, and the distal insulator84 are not shown in FIG. 21 to simplify the drawing. Such conductorswould be formed of high conductivity metals, e.g., copper, copper-silveralloys, and silver cored wire.

In the alternative embodiment of FIGS. 24-26, the extended distalsegment 232 is formed of one or plurality (e.g. two) of spiral woundelectrode(s) 216 supported on a highly flexible or pre-formed electrodesupport tube 214. The proximal end of the extended distal segment 132including the distal insulator 84 is coupled to the intermediate segment34 of the catheter otherwise shown in FIGS. 1 and 8-17 and describedabove. A further insulator 230 separates electrode 112 from theelectrode support tube 214, and the distal tip 228 is fitted to thedistal end of the electrode support tube 214. The conductor(s) to theelectrode(s) 216 that traverse the lumens of the electrode support tube214, the insulator 230, the electrode 112, and the distal insulator 84are not shown in FIG. 21 to simplify the drawing. Such conductor(s)would be formed of high conductivity metals, e.g., copper, copper-silveralloys, and silver cored wire.

It is also contemplated that in the embodiments depicted in FIGS. 24-27may be further modified by eliminating the proximal segment 36 and itsassociated manipulator structure described above. In such an embodiment,the distal end of the proximal section 22 would be coupled directly tothe proximal end of the intermediate segment 34.

In the above-described preferred embodiments, the knuckle bend wire 56and the curve deflection wire 54 extend through the proximal section 22and the curvable proximal segment 36, and the knuckle bend wire 56extends further distally through the bendable intermediate segment 34 ina common radius extending from the catheter body axis 24 as shown inFIGS. 2-16. Therefore, the bend induced in the bendable intermediatesegment 34 upon refraction proximally of the knuckle bend wire 56 andthe curve induced in the curvable proximal segment 36 upon retractionproximally of the curve deflection wire 54 are in a common plane withrespect to the catheter body axis 24 and in a common direction as shownin FIG. 2. The bend induced in the bendable intermediate segment 34 uponretraction proximally of the knuckle bend wire 56 and the curve inducedin the curvable proximal segment 36 upon extension distally of the curvedeflection wire 54 are in a common plane with respect to the catheterbody axis 24 but in a different direction as shown in FIG. 5. Theknuckle bend that can be induced in the intermediate segment 34 is verytight, falling within a radius of about 2.0 mm to 7.0 mm through a rangeof about

−90° to about +180° with respect to the catheter body axis 24 at theintermediate segment proximal end.

It will be understood that certain features of the present invention canbe advantageously employed in modifications of the preferred embodiment,e.g., by displacing the knuckle bend wire 56 and its associated lumens68, 83, 93 and 87, in a radius that is not common with the curvedeflection wire 54 and its associated lumens. In this regard, theknuckle bend wire 56 and its associated lumens 68, 83, 93 and 87, can bearranged in a radius that is diametrically opposed to the radius thatthe curve deflection wire 54 and its associated lumens are aligned with,i.e., in a common diametric line but on either side of the catheter bodyaxis 24. The lateral deflection wire 52 and its associate lumensillustrated in the FIGS. 12-16 occupy such a location, and they can bedisplaced either radially or to the other side of the axis 24. Then, theknuckle bend induced in the intermediate segment 34 would be in theopposite direction than is depicted in FIGS. 2-7.

The catheter shaft or body and handle of the present invention allowsmanipulation with a high degree of sensitivity and controllability toprovide the degree of precision required for proper positioning of thetip electrode(s). The distal section of the catheter body issufficiently resilient in order to position the distal tip electrode(s)against the endocardium and to maintain the distal tip electrode(s) inposition during mapping or ablation without being displaced by movementof the beating heart, by respiration, or by blood flow. Along withsteerability, flexibility, and resiliency, the catheter body has asufficient degree of torsional stiffness to permit user imparted torqueto be transmitted to the distal tip electrode(s) from the handle.Moreover, the catheter body has sufficient column strength to conveyaxial loading to push the distal tip electrode(s) against the tissue attarget positions to be mapped or ablated.

Other modification and variation can be made to the disclosedembodiments without departing from the subject of the invention asdefined in the following claims. For example, materials, diameters andlengths can be changed to suit the particular needs or desires of theuser. A single mapping/ablation electrode, or more than twomapping/ablation electrodes could be present. A plurality of small sizedmapping electrodes displaced apart along the distal section of thecatheter body are typically provided and paired electrically to increasesensing resolution of the electrical signals of the heart traversing theadjoining heart wall site. Mapping electrodes could also be locatedbetween ablation electrodes. In some cases it may be desired to applyenergy to more than one ablation electrode at the same time; forexample, four ablation electrodes could be used and powered in pairs.

Although particular embodiments of the invention have been describedherein in some detail, this has been done for the purpose of providing awritten description of the invention in an enabling manner and to form abasis for establishing equivalents to structure and method steps notspecifically described or listed. It is contemplated by the inventorsthat the scope of the limitations of the following claims encompassesthe described embodiments and equivalents thereto now known and cominginto existence during the term of the patent. Thus, it is expected thatvarious changes, alterations, or modifications may be made to theinvention as described herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A catheter suitable for use in applying ablation energy to body tissue or detecting electrical signals conducted within the body tissue comprising: an elongated catheter body with a smooth outer surface, said elongated catheter body having a catheter body axis and extending between a catheter body proximal end and a catheter body distal end, the elongated catheter body having a catheter body proximal section extending distally from said catheter body proximal end and a deflectable distal tip section extending proximally from said catheter body distal end to a junction with said catheter body proximal section; said deflectable distal tip section including a distal segment, a curvable proximal segment having a proximal segment length and a bendable intermediate segment having an intermediate segment length disposed between the distal segment and the curvable proximal segment; at least one electrode positioned along the distal segment that is adapted to be disposed against body tissue for delivery of ablation energy thereto or for conduction of body tissue electrical signals; a handle at the proximal end of the catheter body, said handle having a proximal handle end and a distal handle end, said handle having a stop plate within said handle distal end; a conductor extending through the catheter body from the handle to the electrode; and an actuation mechanism extending through the catheter body to the deflectable tip section to selectively deflect the catheter body axis in the deflectable distal tip section with respect to the catheter body axis in the catheter body proximal section, the actuation mechanism adapted to curve the proximal segment in a first direction and to bend the intermediate segment in a second direction independently of the curve of the proximal segment to dispose the distal segment at a desired orientation to body tissue, wherein the actuation mechanism further comprises: a first pull wire extending between a first pull wire proximal end disposed within said handle and a first pull wire distal end coupled to said distal segment; a first pull wire lumen formed within said catheter body and extending between a first pull wire lumen proximal end communicating with said handle and a first pull wire lumen distal end, said first pull wire enclosed within said first pull wire lumen, said first pull wire lumen extending in parallel with said catheter body axis and displaced therefrom at a first off-axis location through said proximal and intermediate segments, and said first pull wire distal end affixed to said distal segment; a first pull wire control formed in said handle coupled with said first pull wire proximal end enabling application and release of tension on said first pull wire, said first pull wire control having an extended position wherein said first pull wire is slack and a plurality of retracted positions wherein said first pull wire is retracted and tensioned thereby imparting a knuckle curvature through the intermediate segment length with respect to said proximal segment and deflecting the catheter body axis of said distal segment with respect to the catheter body axis of the catheter body in the catheter body proximal section and the proximal segment; a second pull wire extending between a second pull wire proximal end disposed within said handle and a second pull wire distal end coupled to the junction of said intermediate segment with said proximal segment; a second pull wire lumen formed within said catheter body and extending between a second pull wire lumen proximal end communicating with said handle and a second pull wire lumen distal end, said second pull wire enclosed within said second pull wire lumen, said second pull wire lumen extending in parallel with said catheter body axis and displaced therefrom at a second off-axis location through said proximal segment, and said second pull wire distal end affixed to a junction of said proximal and intermediate segments, said first and second off-axis locations aligned with a common radial direction extending away from the catheter body axis; a second pull wire control formed in said handle coupled with said second pull wire proximal end enabling application and release of tension on said second pull wire independently of application and release of tension on said first pull wire, said second pull wire control having an extended position wherein said second pull wire is slack and a plurality of retracted positions wherein said second pull wire is retracted and tensioned thereby imparting a curvature through the proximal segment length with respect to said distal segment and deflecting the catheter body axis of said proximal segment with respect to the catheter body axis of catheter body in the catheter body proximal section and the distal segment, whereby independent manipulation of the first and second pull wire controls enables a knuckle curvature of the intermediate segment that deflects the distal segment in a first direction with respect to the proximal segment and formation of a curve in the proximal segment in a second direction sharing a common plane with respect to the catheter body axis in the catheter body proximal section and in the distal segment.
 2. The catheter of claim 1, further comprising: a first incompressible wire coil having a first wire coil lumen and extending between a first coil proximal end, said first coil proximal end proximate but not attached to said handle, and a first coil distal end and having a first coil lumen and first coil diameter, said first incompressible coil disposed within said first pull wire lumen with said first coil distal end disposed proximally to said intermediate tip section, and said first pull wire extending through said first incompressible coil lumen, whereby a distal portion of said first pull wire extends distally from said first coil distal end through said intermediate tip section; and a second incompressible wire coil having a second wire coil lumen and extending between a second coil proximal end, said second coil proximal end proximate but not attached to said handle and a second coil distal end and having a second coil lumen and second coil diameter, said second incompressible coil disposed within said second pull wire lumen with said second coil distal end disposed proximally to said proximal tip section, and said second pull wire extending through said second incompressible coil lumen, whereby a distal portion of said second pull wire extends distally from said second coil distal end through said proximal tip section to a junction with said intermediate tip section.
 3. The catheter of claim 2, wherein the intermediate segment capable of bending in a knuckle bend having a radius of between about 2.0 mm and 7.0 mm through a range of about −90° to +180° with respect to the catheter body axis at the intermediate segment proximal end.
 4. The catheter of claim 3, wherein the curve induced in the proximal segment is in the range of about −180° to about +270° with respect to the catheter body axis at the junction of the proximal section with the proximal segment.
 5. A catheter comprising: a catheter body including a center longitudinal axis and a distal tip, the distal tip having a proximal segment, an intermediate segment, and a distal segment; a handle at the proximal end of the catheter body, said handle having a proximal handle end and a distal handle end, said handle having a stop plate within said handle distal end; a first pull wire having a proximal end, a distal end, and a longitudinal axis, the first pull wire forming a first curve having a first radius of curvature in the intermediate segment of the catheter distal tip when the first pull wire moves along the first pull wire longitudinal axis; and a second pull wire having a proximal end, a distal end, and a longitudinal axis, the second pull wire forming a second curve having a second radius of curvature in the proximal segment of the catheter distal tip when the second pull wire moves along the second pull wire longitudinal axis; a first incompressible wire coil having a first wire coil lumen and extending between a first coil proximal end, said first coil proximal end proximate but not attached to said stop plate, and a first coil distal end and having a first coil lumen and first coil diameter, said first pull wire extending through said first incompressible coil lumen, whereby a distal portion of said first pull wire extends distally from said first coil distal end through said intermediate tip section; and a second incompressible wire coil having a second wire coil lumen and extending between a second coil proximal end, said second coil proximal end proximate but not attached to said stop plate and a second coil distal end and having a second coil lumen and second coil diameter, said second pull wire extending through said second incompressible coil lumen, whereby a distal portion of said second pull wire extends distally from said second coil distal end through said proximal tip section to a junction with said intermediate tip section.
 6. The catheter of claim 5, wherein the first radius of curvature is greater than the second degree of curvature.
 7. The catheter of claim 5, wherein the second radius of curvature is greater than the first degree of curvature.
 8. The catheter of claim 5 wherein the catheter body longitudinal axis is at 0°, and the distal tip is deflected at the intermediate segment to between approximately −90° and approximately 180° from the catheter body center longitudinal axis.
 9. The catheter of claim 8, wherein the distal tip is deflected at the proximal segment to between approximately −90° and approximately 270° from the catheter body center longitudinal axis.
 10. The catheter of claim 9, wherein the first pull wire and second pull wire are each positioned parallel to the catheter body center longitudinal axis, the first pull wire being at a first off-center location and the second pull wire being at a second off-center location, the first and second off-center locations being in a common radial direction from the center longitudinal axis.
 11. The catheter of claim 9, wherein the first pull wire distal end is affixed to the intermediate segment of the distal tip and the second pull wire distal end is affixed to the proximal segment of the distal tip. 